EP1366199B1 - Production of a cylindrical housing for a double screw extruder - Google Patents

Production of a cylindrical housing for a double screw extruder Download PDF

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Publication number
EP1366199B1
EP1366199B1 EP02729775A EP02729775A EP1366199B1 EP 1366199 B1 EP1366199 B1 EP 1366199B1 EP 02729775 A EP02729775 A EP 02729775A EP 02729775 A EP02729775 A EP 02729775A EP 1366199 B1 EP1366199 B1 EP 1366199B1
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EP
European Patent Office
Prior art keywords
inductor
spectacle hole
hole
spectacle
areas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP02729775A
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German (de)
French (fr)
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EP1366199A2 (en
Inventor
Michael Behling
Volker Wesling
Uwe Motzkau
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KraussMaffei Berstorff GmbH
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Berstorff GmbH
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/06—Surface hardening
    • C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
    • C21D1/10—Surface hardening by direct application of electrical or wave energy; by particle radiation by electric induction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49229—Prime mover or fluid pump making
    • Y10T29/4927—Cylinder, cylinder head or engine valve sleeve making

Definitions

  • the invention relates to a method for producing a cylinder housing of a twin-screw extruder, the worms meshing with wear-resistant inner surface of a steel block by introducing two continuous and partially overlapping holes (eyeglass bore) in the steel block and then hardening the inner surface of the eyeglass bore and a device for curing the inner surface of the eyeglass bore.
  • Twin-screw extruders with tightly intermeshing screws have cylinder housings composed of axial sections, which have a continuous bore in which the respective two extruder screws rotate at a small distance from the inner surface.
  • the inner surface of the cylinder bore is subject to abrasive wear, which has two main causes.
  • One of the causes is the processing of feedstocks with aggressive properties, eg plastics with abrasive fillers.
  • radial deflections of the worm shaft and consequently sliding contacts between the outer surface of the worm and the inner surface of the cylinder housing can occur.
  • cylinder housings which are made of a steel block, in which the two partially overlapping holes for the two screws are introduced and in which subsequently the inner surface is cured. This is usually done by the mechanically machined workpiece is inserted into a curing oven, brought to hardening temperature and then quenched. In this case, a hardening of the workpiece is achieved, which is not desirable in Regetfall. On the one hand, this applies to the flanges of the sections of the cylinder housing, with which this be connected together to form a coherent housing.
  • inductive heating in uniform form, ie with constant penetration depth without large problems with workpieces with even contour.
  • inductive heating is practiced particularly successfully in the heating of steel tubes with a circular cross-section.
  • inductor shaped in the same way as the housing cross-section would lead to very unevenly high heating and penetration depths.
  • the gusset areas would namely be acted upon by particularly high heat energy, since the energy input would take place there as it were from two cylinder bores. In the gusset area would thus take place in the subsequent cooling under curing conditions virtually a through hardening. This would mean that these areas would be particularly sensitive to breakage. For this reason, such hardening by inductive hardening is not practiced so far.
  • Object of the present invention is to develop a method of the generic type such that the time and cost complexity for achieving a hardening of the inner surface of a cylinder housing for a twin-screw extruder is minimized, the penetration depth of the curing limited and as equal to the circumference of the Eyeglass bore should be. Furthermore, a device for carrying out such a hardening treatment should be specified.
  • the invention provides that after the introduction of the eyeglass bore in the steel block used for the production of a cylinder housing or housing section, the hardening of the inner surface of the eyeglass bore is performed by induction hardening.
  • the penetration depth is maintained substantially at a constant value by using an electrical inductor which has an inner contour of the eyeglass bore approximately corresponding reduced form and is passed from one end of the eyeglass bore to the other end through this.
  • this inductor is designed in such a way that, in the vicinity of the two gussets of the eyeglass bore, significantly less energy for heating the inner surface of the eyeglass bore is emitted relative to the associated longitudinal section on the circumference of the eyeglass than in the regions of the inner contour that are more remote from the gussets.
  • the specific heat energy input can be metered so that in the gusset region at least approximately in the material zone, which is in each case close to the inner surface and is provided for hardening, an approximately equal heating takes place as in the further removed from the two gusset areas surface areas. In this way, unwanted hardening of large parts of the gusset region can be avoided. In this way, the desired ductility in the volume parts of the housing wall that are further away from the bore surfaces also remains in the required extent in the interstice area.
  • a minimum cooling rate after heating to hardening temperature is required to carry out the inductive hardening.
  • a cooling device for accelerating the cooling of the inductively heated areas is advantageously passed through the glasses bore in a short axial distance behind the inductor. In this way, the inner surface is heated over a short part of its axial length and immediately thereafter successively quenched.
  • the hardening takes place in a spatially continuous process.
  • the invention provides for guiding the inductor in the vicinity of the two gussets with a distance from the inner surface through the housing bores that is significantly larger than the remaining area of the inner contour of the gland bore. The greater the distance of the inductor from the housing surface, the less heat energy can be introduced by the inductor in the respective surface area.
  • the process parameters amperage and frequency of the inductor current should be mentioned in particular.
  • the frequency can be changed in a conventional manner, the penetration depth, while the size of the inductor current for the recoverable heat output is relevant. Therefore, the heat input can also be influenced by the choice of the turn-on time of the inductor during its passage through the eyeglass bore.
  • an inductor is used which has independently controllable sections over the length of its circumference. It may therefore be provided that the one or more inductor sections located in the immediate vicinity of the interstices are, for example, timed, so that they are not constantly in operation during the entire treatment time. But they can also be operated with constant, but compared to the more distant from the gussets areas of reduced electrical power.
  • the inventive method can be performed on cylinder housings, which are made of a relatively inexpensive metallic material and whose inner surface has been plated with a high-quality curable material, so that this is a composite material.
  • the heating can also take place indirectly over the base material, if a non-magnetic material is used for plating. This is applied before the mechanical processing of the eyeglass bore is completed. The surface of the cladding is thus also mechanically processed before the curing takes place.
  • An inventive device for inductive hardening of the inner surface of a spectacle bore in a cylinder housing made of steel for a screw extruder which is used in particular for carrying out the curing in a manufacturing process according to the invention, has an electrical inductor whose outer shape corresponds approximately to a reduction of the inner contour of the eyeglass bore , wherein the inductor is designed in such a way that in the vicinity of the two gusset of the eyeglass bore relative to the associated length portion on the circumference of the inductor respectively significantly less energy is emitted to heat the inner surface than in the more remote from the gussets areas of the inner surface.
  • an inductor as a continuous electrical conductor, which has approximately the outer contour of an "8" bent from an electrically conductive tube, preferably from a copper tube.
  • a coolant can be passed through this tube.
  • the shape of the inductor is designed so that the upper and lower portions of the "8" are each bent in a circle, while with increasing approach to the central region of the "8", which corresponds to the Zwicket Scheme the eyeglass bore, each an area with increasingly smaller radius of curvature connects In the actual central region of the "8" is provided in each case a counter-arc to connect the areas with the smaller radius of curvature in pairs.
  • the inductor can also be divided into a plurality of electrically independently controllable sections.
  • the inductor is thus not designed as a continuous electrical conductor, but constructed of electrically mutually insulated sections, which in turn, however, in their sum can have the approximated to an "8" outer contour.
  • it can also be provided to construct the inductor practically of two separate parts, which correspond in their outer shape to the two parts of the eyeglass bore, ie the respective overlapping housing bores.
  • the regions close to the vicinity of the inductor have a greater distance from the inner surface than the regions which are further away from the gussets.
  • a subdivision of the two parts of the inductor can also be selected in independently controllable sections.
  • a cooling device is arranged at a short axial distance behind the inductor, by means of which the surface regions of the eyeglass bore heated by the inductor as it passes through the eyeglass bore can be cooled down more rapidly.
  • This cooling device is preferably formed from a, similar to a "8" curved, circulating manifold whose contour is adapted in size to each of the eyeglass bore to be treated.
  • This distributor tube has a multiplicity of nozzles for a flowable coolant, in particular for a cooling gas, positioned radially outwards and obliquely against the intended direction of movement of the device.
  • FIGS. 1-4 each show, in a cross-section, a cylinder housing 1 with a bore 2 made of two partially overlapping housing bores.
  • the cylinder housing 1 has been produced from a block of hardenable steel by machining processes.
  • the housing wall in the form of the two gussets 4 a, 4 b designed.
  • Such a gusset is shown enlarged in the figure 6 as a partial detail.
  • the inner surface of the cylinder housing 1 is to be hardened so that the hardened layer 17 has only a very limited depth of e.g. 0.5-2 mm. This is to avoid that the gussets 4 a, 4 b are cured and thus lose their ductility in the interior.
  • an electrical inductor 3 is arranged in FIG. 1, which is bent substantially in the form of a horizontal "8" as a continuous electrical conductor, for example, of a copper tube.
  • the inductor 3 is composed of several sections with different curvature.
  • the two sections 6 a and 6 b each have a constant radius of curvature, which ensures that the distance between these sections of the inner surface of the eyeglass bore 2 is constant.
  • the sections 7 a - 7 d are provided, which have in the direction of the central region of the "8" an increasingly smaller radius of curvature, so that in these areas, the distance of the inductor from the inner surface the eyeglass bore increased accordingly.
  • the two opposing arches 8 a and 8 b are provided.
  • the counter-bow 8 b is executed divided in principle, since the two electrical connections for the introduction of the inductor are arranged on it. These connections are indicated by two small circles.
  • FIG 2 another embodiment of the inductor 3 is shown in which individual sections in the vicinity of the two gussets 4 a, 4 b are electrically controlled independently of each other, so have separate inductive power connections.
  • the distance to the inner surface of the eyeglass bore 2 remains practically constant over the entire circumference.
  • the inductor 3 consists in each case of two circularly bent sections 9 a, 9 b whose circumference is greater than in the case of a semicircle.
  • At each end of the two sections 9 a, 9 b close in succession in each case two shorter sections 10 a, 11 a and 10 b, 11 b and 10 c, 11 c and 10 d, 11 d of the inductor.
  • the portions 10 a -10 d are operated with the same electrical parameters, that are connected to the same power source.
  • These can be compared to the sections 9 a, 9 b to reduce the specific heat input in the region of the gusset 4 a, 4 b in particular with reduced inductor and / or operated in time.
  • FIG. 3 shows a variant of the inductor 3 in which a total of four independently controllable sections 12 a, 12 b, 13 a, 13 b are provided.
  • the two sections 12 a, 12 b have a constant radius of curvature, while arranged in the vicinity of the two gussets 4 a, 4 b inductor sections 13 a, 13 b are curved so that their distance from the inner surface with increasing approach to the tip region of the respective gusset 4 a and 4 b is larger.
  • the two sections 13 a, 13 b are operated with respect to the two sections 12 a, 12 b reduced electrical power.
  • FIG 4 a variant of the inductor 3 is shown, in which this consists of two sections 14 a, 14 b, which are each operated with the same electrical parameters, that is preferably connected to the same electrical power source. Similar to Figure 1 and Figure 3, the inductor 3 with increasing approach to the two gusset regions 4 a, 4 b an increasing distance from the inner surface of the eyeglass bore 2.
  • a cooling device 15 is shown within a spectacle bore 2 of a cylinder housing 1, which is arranged at an axial distance behind the inductor, not shown here and is passed together with the inductor through the eyeglass bore 2 in the audatory direction.
  • This cooling device 15 is designed in the form of a circulating Verteiterrohres, which is bent substantially in the form of an "8" and in this respect is adapted to the contour of the eyeglass bore 2.
  • the manifold is provided with a supply line for a cooling medium, not shown, as well as at its periphery with numerous radially outwardly directed nozzles 16 through which a gaseous or liquid cooling medium can escape.
  • the nozzles 16 are made obliquely backwards with respect to the direction of movement of the inductor during the hardening process against the direction of movement, so that not the still heated areas of the inner surface are cooled, but only the already brought to hardening temperature surface areas.
  • cylinder housings of twin-screw extruders can be provided much more cost-effectively with a largely uniformly thick hardening layer in the region of the inner surface than has hitherto been the case, since elaborate annealing of the entire cylinder housing in a furnace can be omitted. Not only a considerable energy saving is achieved, but it is also achieved a drastic reduction in treatment time. It is essential that with the procedure according to invention and by the employment of an inductor according to invention an unwanted hardening of the Zwickei Avenuee stops.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Extrusion Of Metal (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Herstellung eines Zylindergehäuses eines Doppelschneckenextruders, dessen Schnecken miteinander kämmen, mit verschleißfester Innenoberfläche aus einem Stahlblock durch Einbringung zweier durchgehender und sich teilweise überlappender Bohrungen (Brillenbohrung) in den Stahlblock und anschließendes Härten der Innenoberfläche der Brillenbohrung sowie eine Vorrichtung zum Härten der Innenoberfläche der Brillenbohrung.The invention relates to a method for producing a cylinder housing of a twin-screw extruder, the worms meshing with wear-resistant inner surface of a steel block by introducing two continuous and partially overlapping holes (eyeglass bore) in the steel block and then hardening the inner surface of the eyeglass bore and a device for curing the inner surface of the eyeglass bore.

Doppelschneckenextruder mit dicht kämmenden Schnecken weisen aus axialen Teilabschnitten zusammengesetzte Zylindergehäuse auf, die eine durchgehende Brillenbohrung besitzen, in denen sich die jeweiligen beiden Extruderschnecken mit geringem Abstand zur Innenoberfläche drehen. Die Innenoberfläche der Zylinderbohrung unterliegt dabei einem abrasiven Verschleiß, der im Wesentlichen zwei Ursachen hat. Die eine Ursache ist in der Verarbeitung von Einsatzmaterialien mit aggressiven Eigenschaften, z.B. Kunststoffe mit abrasiv wirkenden Füllstoffen, zu sehen. Zum anderen kann es durch die während der Verarbeitung im Inneren des Zylinders auftretenden Druckverhältnisse zu radialen Auslenkungen der Schneckenwelle und demzufolge zu gleitenden Berührungen zwischen der Außenoberfläche der Schnecke und der Innenoberfläche des Zylindergehäuses kommen. Aus diesem Grunde werden nach Möglichkeit Zylindergehäuse verwendet, die aus einem Stahlblock hergestellt sind, in den die beiden sich teilweise überlappenden Bohrungen für die beiden Schnecken eingebracht werden und bei denen anschließend die Innenoberfläche gehärtet wird. Dies erfolgt üblicherweise dadurch, dass das mechanisch bearbeitete Werkstück in einen Härteofen eingesetzt, auf Härtetemperatur gebracht und anschließend abgeschreckt wird. Dabei wird eine Durchhärtung des Werkstücks erzielt, die im Regetfall aber nicht erwünscht ist. Zum einen gilt dies für die Flansche der Abschnitte des Zylindergehäuses, mit denen diese untereinander zu einem zusammenhängenden Gehäuse verbunden werden. Zum anderen gilt dies für die beiden Zwickelbereiche der Brillenbohrung des Zylindergehäuses, d.h. für die Gehäusebereiche in der Nähe der Überlappungszone der beiden durch das Gehäuse verlaufenden Bohrungen. An diesen Stellen ist es nämlich erwünscht, dass das Gehäuse zur Vermeidung von Brüchen möglichst gute Zähigkeitseigenschaften aufweist, die aber durch eine Durchhärtung regelmäßig verloren gehen. Hinzu kommt, dass die Kosten einer solchen Härtebehandlung relativ hoch sind, weil diese in erster Linie von der Höhe des Gewichts der Werkstücke abhängt und ein Gehäuseabschnitt für einen Doppelschneckenextruder wegen der großen erforderlichen Wanddicken sehr schwer ist.Twin-screw extruders with tightly intermeshing screws have cylinder housings composed of axial sections, which have a continuous bore in which the respective two extruder screws rotate at a small distance from the inner surface. The inner surface of the cylinder bore is subject to abrasive wear, which has two main causes. One of the causes is the processing of feedstocks with aggressive properties, eg plastics with abrasive fillers. On the other hand, due to the pressure conditions occurring in the interior of the cylinder during processing, radial deflections of the worm shaft and consequently sliding contacts between the outer surface of the worm and the inner surface of the cylinder housing can occur. For this reason, if possible cylinder housings are used, which are made of a steel block, in which the two partially overlapping holes for the two screws are introduced and in which subsequently the inner surface is cured. This is usually done by the mechanically machined workpiece is inserted into a curing oven, brought to hardening temperature and then quenched. In this case, a hardening of the workpiece is achieved, which is not desirable in Regetfall. On the one hand, this applies to the flanges of the sections of the cylinder housing, with which this be connected together to form a coherent housing. On the other hand, this applies to the two gusset areas of the eyeglass bore of the cylinder housing, ie for the housing areas in the vicinity of the overlapping zone of the two holes extending through the housing. In fact, at these points, it is desirable for the case to have the best possible toughness properties in order to avoid fractures, but these are regularly lost through through-hardening. In addition, the cost of such hardening treatment is relatively high, because it depends primarily on the height of the weight of the workpieces and a housing section for a twin-screw extruder is very difficult because of the large required wall thicknesses.

Es ist bekannt, an Werkstücken durch eine Einsatzhärtung die Aufhärtung gezielt auf den Oberflächenbereich des jeweiligen Werkstücks zu beschränken, so dass das Werkstück im überwiegenden Teil seiner Masse im Wesentlichen die ursprünglich gegebenen guten Zähigkeitseigenschaften behält. Hierzu wird das aus kohlenstoffarmem Stahl gefertigte Werkstück in einen Ofen eingesetzt, in dem eine kohlenstoffreiche Atmosphäre aufrecht erhalten wird, so dass durch Diffusion des Kohlenstoffs in den Stahl eine Aufkohlung in einem solchen Maße stattfindet, dass durch anschließende Kühlung dann der gewünschte Härteeffekt erzielt wird. In ähnlicher Weise kann durch gezieltes Eindiffundieren von Stickstoff in den Stahl ein Nitrierhärten im Oberflächenbereich durchgeführt werden. Wegen der erforderlichen langen Glühzeiten sind solche Verfahren jedoch besonders kostenaufwendig.It is known to limit the hardening of workpieces by a case hardening specifically to the surface area of the respective workpiece, so that the workpiece retains substantially the originally given good toughness properties in the majority of its mass. For this purpose, the workpiece made of low-carbon steel is inserted into a furnace in which a carbon-rich atmosphere is maintained, so that by diffusion of the carbon into the steel carburization takes place to such an extent that then the desired hardening effect is achieved by subsequent cooling. Similarly, nitridation in the surface region can be carried out by deliberate diffusion of nitrogen into the steel. However, because of the required long annealing times, such processes are particularly costly.

Es ist aber auch grundsätzlich bekannt, ein Oberflächenhärten dadurch auszuführen, dass man einen an sich härtbaren Stahl nur an der Oberfläche, d.h. bis zu einer begrenzten Eindringtiefe erwärmt und anschließend abschreckt. Die Erwärmung kann durch Flammen oder auch durch induktives Erwärmen erzielt werden. Bei letzterem werden durch einen Induktor im zu behandelnden Werkstück elektrische Wirbeiströme induziert, die insbesondere infolge der Ummagnetisierung des Werkstücks zu einer Erwärmung führen.However, it is also basically known to carry out a surface hardening by using a curable steel only at the surface, i. heated to a limited penetration depth and then quenched. The heating can be achieved by flame or by inductive heating. In the latter, electrical swirling currents are induced by an inductor in the workpiece to be treated, which leads to a heating, in particular as a result of the remagnetization of the workpiece.

Grundsätzlich lässt sich eine induktive Erwärmung in gleichmäßiger Form, d.h. mit gleichbleibender Eindringtiefe ohne große Probleme an Werkstücken mit gleichmäßiger Kontur durchführen. So wird etwa die induktive Erwärmung besonders erfolgreich praktiziert bei der Aufheizung von Stahlrohren mit kreisrundem Querschnitt. Bei Zylindergehäusen für einen Doppelschneckenextruder würde allerdings ein induktives Erwärmen mittels eines in entsprechender Weise wie der Gehäusequerschnitt geformten Induktors zu sehr ungleichmäßig starken Erwärmungen und Eindringtiefen führen. Die Zwickelbereiche würden nämlich mit besonders hoher Wärmeenergie beaufschlagt werden, da der Energieeintrag dort gleichsam von beiden Zylinderbohrungen aus erfolgen würde. Im Zwickelbereich würde also bei der anschließenden Abkühlung unter Aufhärtungsbedingungen praktisch eine Durchhärtung stattfinden. Diese hätte zur Folge, dass diese Bereiche besonders bruchempfindlich werden würden. Aus diesem Grunde wird eine solche Aufhärtung durch induktives Härten bisher nicht praktiziert.Basically, an inductive heating in uniform form, ie with constant penetration depth without large problems with workpieces with even contour. For example, inductive heating is practiced particularly successfully in the heating of steel tubes with a circular cross-section. In cylindrical housings for a twin-screw extruder, however, inductive heating by means of an inductor shaped in the same way as the housing cross-section would lead to very unevenly high heating and penetration depths. The gusset areas would namely be acted upon by particularly high heat energy, since the energy input would take place there as it were from two cylinder bores. In the gusset area would thus take place in the subsequent cooling under curing conditions virtually a through hardening. This would mean that these areas would be particularly sensitive to breakage. For this reason, such hardening by inductive hardening is not practiced so far.

Aufgabe der vorliegenden Erfindung ist es, ein Verfahren der gattungsgemäßen Art dahingehend weiterzubilden, dass der zeitliche und kostenmäßige Aufwand für die Erzielung einer Aufhärtung der Innenoberfläche eines Zylindergehäuses für einen Doppelschneckenextruder möglichst gering ist, wobei die Eindringtiefe der Härtung begrenzt und möglichst gleich über den Umfang der Brillenbohrung sein soll. Femer soll eine Vorrichtung zur Durchführung einer solchen Härtebehandlung angegeben werden.Object of the present invention is to develop a method of the generic type such that the time and cost complexity for achieving a hardening of the inner surface of a cylinder housing for a twin-screw extruder is minimized, the penetration depth of the curing limited and as equal to the circumference of the Eyeglass bore should be. Furthermore, a device for carrying out such a hardening treatment should be specified.

Gelöst wird diese Aufgabe hinsichtlich des Verfahrens mit den im Patentanspruch 1 angegebenen Merkmalen. Durch die Merkmale der Unteransprüche 2 - 6 lässt sich dieses Verfahren in vorteilhafter Weise weiterbilden. Eine erfindungsgemäße Vorrichtung weist die im Patentanspruch 6 angegebenen Merkmale auf. Aus den Unteransprüchen 8-11 ergeben sich vorteilhafte Weiterbildungen dieser Vorrichtung.This object is achieved with regard to the method with the features specified in claim 1. By the features of the subclaims 2-6, this method can be further developed in an advantageous manner. A device according to the invention has the features specified in claim 6. From the dependent claims 8-11 advantageous developments of this device.

Die Erfindung sieht vor, dass nach Einbringung der Brillenbohrung in den für die Herstellung eines Zylindergehäuses bzw. -gehäuseabschnitts eingesetzten Stahlblock die Härtung der Innenoberfläche der Brillenbohrung durch Induktives Härten vorgenommen wird. Dabei wird die Eindringtiefe im Wesentlichen auf einem gleichbleibenden Wert gehalten, indem ein elektrischer Induktor verwendet wird, der eine der Innenkontur der Brillenbohrung annähernd entsprechende verkleinerte Form aufweist und von einem Ende der Brillenbohrung bis zu deren anderem Ende durch diese hindurchgeführt wird. Dieser Induktor ist erfindungsgemäß darauf ausgelegt, dass im Nahbereich der beiden Zwickel der Brillenbohrung bezogen auf den zugeordneten Längenabschnitt am Umfang des Induktors jeweils deutlich weniger Energie zur Erwärmung der Innenoberfläche der Brillenbohrung abgegeben wird als in den von den Zwickeln entfernteren Bereichen der Innenkontur. Das hat zur Folge, dass die einzelnen Volumenelemente im Bereich der Zwickel, die sowohl in der Nähe der einen wie auch der anderen Gehäusebohrung liegen und daher einen Wärmeeintrag über die Innenoberfläche beider Bohrungen erfahren, insgesamt weniger erwärmt werden, als wenn bezogen auf die Innenoberfläche der Gehäusebohrungen überall ein gleicher Wärmeenergieeintrag (spezifischer Wärmeenergieeintrag) erfolgt. Der spezifische Wärmeenergieeintrag kann so dosiert werden, dass im Zwickelbereich zumindest annähernd in der Materialzone, die jeweils nahe an der Innenoberfläche liegt und zur Aufhärtung vorgesehen ist, eine etwa gleich starke Erwärmung erfolgt wie in den weiter von den beiden Zwickelbereichen entfernten Oberflächenbereichen. Auf diese Weise kann eine unerwünschte Durchhärtung großer Teile des Zwickelbereichs vermieden werden. Damit bleibt die erwünschte Duktilität in den von den Bohrungsoberflächen weiter entfernten Volumenteilen der Gehäusewand auch im Zwickelbereich im jeweils erforderlichen Maß erhalten.The invention provides that after the introduction of the eyeglass bore in the steel block used for the production of a cylinder housing or housing section, the hardening of the inner surface of the eyeglass bore is performed by induction hardening. In this case, the penetration depth is maintained substantially at a constant value by using an electrical inductor which has an inner contour of the eyeglass bore approximately corresponding reduced form and is passed from one end of the eyeglass bore to the other end through this. According to the invention, this inductor is designed in such a way that, in the vicinity of the two gussets of the eyeglass bore, significantly less energy for heating the inner surface of the eyeglass bore is emitted relative to the associated longitudinal section on the circumference of the eyeglass than in the regions of the inner contour that are more remote from the gussets. This has the consequence that the individual volume elements in the region of the gusset, which are both in the vicinity of one and the other housing bore and therefore experience a heat input via the inner surface of both holes, are heated less than when relative to the inner surface of the Housing bores everywhere the same heat energy input (specific heat energy input) takes place. The specific heat energy input can be metered so that in the gusset region at least approximately in the material zone, which is in each case close to the inner surface and is provided for hardening, an approximately equal heating takes place as in the further removed from the two gusset areas surface areas. In this way, unwanted hardening of large parts of the gusset region can be avoided. In this way, the desired ductility in the volume parts of the housing wall that are further away from the bore surfaces also remains in the required extent in the interstice area.

Je nach Art des für das Zylindergehäuse eingesetzten Stahlwerkstoffs ist zur Durchführung der induktiven Härtung eine Mindestabkühlgeschwindigkeit nach der Erwärmung auf Härtetemperatur erforderlich. Bei sogenannten Lufthärtem reicht eine normale Abkühlung an ruhender Luft völlig aus, zumal Wärme aus den oberflächennahen Bereichen in die nicht induktiv erwärmten Volumenelemente der Gehäusewand des Zylindergehäuses abfließen kann. Bei Werkstoffen, die eine schroffere Abkühlung erfordern, wird vorteilhaft in einem kurzen axialen Abstand hinter dem Induktor eine Kühleinrichtung zur Beschleunigung der Abkühlung der induktiv erhitzten Bereiche durch die Brillen bohrung hindurchgeführt. Auf diese Weise wird die Innenoberfläche über einen kurzen Teil ihrer axialen Länge jeweils erwärmt und unmittelbar danach sukzessive abgeschreckt. Das Härten erfolgt hierbei also in einem räumlich kontinuierlich fortschreitenden Verfahren. Je nach gewünschter Größe der Abkühlgeschwindigkeit können flüssige (z.B. Wasser) oder gasförmige (z.B. Luft) Kühlmittel für die beschleunigte Abkühlung verwendet werden.Depending on the type of steel material used for the cylinder housing, a minimum cooling rate after heating to hardening temperature is required to carry out the inductive hardening. In so-called Luftärtem a normal cooling of static air is sufficient, especially since heat from the near-surface areas can flow into the non-inductively heated volume elements of the housing wall of the cylinder housing. For materials that require a more rapid cooling, a cooling device for accelerating the cooling of the inductively heated areas is advantageously passed through the glasses bore in a short axial distance behind the inductor. In this way, the inner surface is heated over a short part of its axial length and immediately thereafter successively quenched. The hardening takes place in a spatially continuous process. Depending on the desired size of Cooling rate can be used liquid (eg water) or gaseous (eg air) coolant for the accelerated cooling.

Die Verminderung des spezifischen Wärmeenergieeintrags im Nahbereich der beiden Zwickel der Brillenbohrung lässt sich auf unterschiedliche Weise bewirken. In einer Ausführungsform sieht die Erfindung vor, den Induktor im Nahbereich der beiden Zwickel mit einem gegenüber dem übrigen Bereich der Innenkontur der Brillenbohrung deutlich vergrößerten Abstand von der Innenoberfläche durch die Gehäusebohrungen zu führen. Je größer der Abstand des induktors von der Gehäuseoberfläche ist, umso weniger Wärmeenergie kann durch den Induktor in den jeweiligen Oberflächenbereich eingetragen werden.The reduction of the specific heat energy input in the vicinity of the two gussets of the eyeglass bore can be effected in different ways. In one embodiment, the invention provides for guiding the inductor in the vicinity of the two gussets with a distance from the inner surface through the housing bores that is significantly larger than the remaining area of the inner contour of the gland bore. The greater the distance of the inductor from the housing surface, the less heat energy can be introduced by the inductor in the respective surface area.

Eine andere Möglichkeit besteht darin, die elektrischen Betriebsparameter des Induktors bezogen auf den Umfang der Innenoberfläche bereichsweise zu ändern. In diesem Zusammenhang sind insbesondere die Verfahrensparameter Stromstärke und Frequenz des Induktorstroms zu nennen. Durch die Wahl der Frequenz lässt sich in an sich bekannter Weise die Eindringtiefe verändem, während die Größe des Induktorstroms für die einbringbare Wärmeleistung maßgeblich ist. Daher lässt sich der Wärmeeintrag auch durch die Wahl der Anschaltzeit des Induktors während seiner Hindurchführung durch die Brillenbohrung beeinflussen. Vorzugsweise wird ein Induktor eingesetzt, der über die Länge seines Umfangs elektrisch unabhängig voneinander steuerbare Abschnitte aufweist. Es kann also vorgesehen sein, den oder die in unmittelbarer Nähe der Zwickelbereiche gelegenen Induktorabschnitte beispielsweise zeitlich getaktet anzusteuem, so dass sie nicht während der gesamten Behandlungszeit ständig in Betrieb sind. Sie können aber auch mit konstanter, aber gegenüber den von den Zwickeln weiter entfernten Bereichen verminderter elektrischer Leistung betrieben werden.Another possibility is to change the electrical operating parameters of the inductor in relation to the circumference of the inner surface area. In this context, the process parameters amperage and frequency of the inductor current should be mentioned in particular. By choosing the frequency can be changed in a conventional manner, the penetration depth, while the size of the inductor current for the recoverable heat output is relevant. Therefore, the heat input can also be influenced by the choice of the turn-on time of the inductor during its passage through the eyeglass bore. Preferably, an inductor is used which has independently controllable sections over the length of its circumference. It may therefore be provided that the one or more inductor sections located in the immediate vicinity of the interstices are, for example, timed, so that they are not constantly in operation during the entire treatment time. But they can also be operated with constant, but compared to the more distant from the gussets areas of reduced electrical power.

Selbstverständlich ist es auch möglich, neben einer Beeinflussung der Betriebsparameter zusätzlich auch die Verfahrensweise einzusetzen, bei der der Abstand des Induktors zur Innenoberfläche der Brillenbohrung über seinen Umfang gezielt ungleich eingestellt wird.Of course, it is also possible, in addition to influencing the operating parameters, to additionally use the procedure in which the distance between the inductor and the inner surface of the eyeglass bore is deliberately set unequally over its circumference.

Mit besonderem Vorteil lässt sich das erfindungsgemäße Verfahren an Zylindergehäusen ausführen, die aus einem vergleichsweise kostengünstigen metallischen Werkstoff hergestellt sind und deren Innenoberfläche mit einem hochwertigen härtbaren Werkstoff plattiert worden ist, so dass es sich hierbei um einen Verbundwerkstoff handelt. Dabei kann die Erwärmung auch indirekt über den Grundwerkstoff erfolgen, wenn zur Plattierung ein unmagnetischer Werkstoff verwendet wird. Dieser wird aufgebracht, bevor die mechanische Bearbeitung der Brillenbohrung beendet ist. Die Oberfläche der Plattierung wird also ebenfalls noch mechanisch bearbeitet, bevor die Härtung erfolgt.With particular advantage, the inventive method can be performed on cylinder housings, which are made of a relatively inexpensive metallic material and whose inner surface has been plated with a high-quality curable material, so that this is a composite material. The heating can also take place indirectly over the base material, if a non-magnetic material is used for plating. This is applied before the mechanical processing of the eyeglass bore is completed. The surface of the cladding is thus also mechanically processed before the curing takes place.

Eine erfindungsgemäße Vorrichtung zur induktiven Härtung der Innenoberfläche einer Brillenbohrung in einem Zylindergehäuse aus Stahl für einen Schneckenextruder, die insbesondere zur Durchführung des Härtens im Rahmen eines erfindungsgemäßen Herstellverfahrens eingesetzt wird, weist einen elektrischen Induktor auf, dessen äußere Form annähernd einer Verkleinerung der Innenkontur der Brillenbohrung entspricht, wobei der Induktor in der Weise ausgelegt ist, dass im Nahbereich der beiden Zwickel der Brillenbohrung bezogen auf den zugeordneten Längenabschnitt am Umfang des Induktors jeweils deutlich weniger Energie zur Erwärmung der Innenoberfläche abgegeben wird als in den von den Zwickeln entfernteren Bereichen der Innenoberfläche.An inventive device for inductive hardening of the inner surface of a spectacle bore in a cylinder housing made of steel for a screw extruder, which is used in particular for carrying out the curing in a manufacturing process according to the invention, has an electrical inductor whose outer shape corresponds approximately to a reduction of the inner contour of the eyeglass bore , wherein the inductor is designed in such a way that in the vicinity of the two gusset of the eyeglass bore relative to the associated length portion on the circumference of the inductor respectively significantly less energy is emitted to heat the inner surface than in the more remote from the gussets areas of the inner surface.

Vorzugsweise wird ein Induktor als zusammenhängender elektrischer Leiter, der etwa die Außenkontur einer "8" aufweist aus einem elektrisch leitenden Rohr gebogen, vorzugsweise aus einem Kupferrohr. Zur Kühlung des Induktors kann durch dieses Rohr ein Kühlmittel geführt werden. Die Form des Induktors ist so gestaltet, dass die oberen und unteren Bereiche der "8" jeweils kreisförmig gebogen sind, während sich mit zunehmender Annäherung an den Mittelbereich der "8", der dem Zwicketbereich der Brillenbohrung entspricht, jeweils ein Bereich mit zunehmend kleinerem Krümmungsradius anschließt Im eigentlichen Mittelbereich der "8" ist jeweils ein Gegenbogen vorgesehen, um die Bereiche mit dem kleineren Krümmungsradius paarweise miteinander zu verbinden. Durch die Veränderung des Krümmungsradius wird erreicht, dass die jeweiligen Teilbereiche am Umfang des Induktors beim Hindurchführen durch die Brillenbohrung des Zylindergehäuses einen unterschiedlichen Abstand von der Innenoberfläche aufweisen.Preferably, an inductor as a continuous electrical conductor, which has approximately the outer contour of an "8" bent from an electrically conductive tube, preferably from a copper tube. To cool the inductor, a coolant can be passed through this tube. The shape of the inductor is designed so that the upper and lower portions of the "8" are each bent in a circle, while with increasing approach to the central region of the "8", which corresponds to the Zwicketbereich the eyeglass bore, each an area with increasingly smaller radius of curvature connects In the actual central region of the "8" is provided in each case a counter-arc to connect the areas with the smaller radius of curvature in pairs. By changing the radius of curvature is achieved that the respective sections on the circumference of the inductor during Passing through the eyeglass bore of the cylinder housing have a different distance from the inner surface.

Alternativ oder zusätzlich kann der Induktor auch in mehrere elektrisch unabhängig voneinander steuerbare Abschnitte aufgeteilt sein. In diesem Fall ist der Induktor also nicht als zusammenhängender elektrischer Leiter ausgeführt, sondern aus elektrisch gegeneinander isolierten Teilabschnitten aufgebaut, die allerdings in ihrer Summe wiederum die an eine "8" angenäherte Außenkontur aufweisen können. Es kann aber auch vorgesehen sein, den Induktor praktisch aus zwei separaten Teilen aufzubauen, die in ihrer äußeren Gestalt den beiden Teilen der Brillenbohrung, also den jeweils sich überlappenden Gehäusebohrungen entsprechen. Dabei ist wiederum vorgesehen, dass die zwickelnahen Bereiche des Induktors von der Innenoberfläche einen größeren Abstand aufweisen als die von den Zwickeln weiter entfernten Bereiche. Alternativ oder zusätzlich kann auch hier eine Unterteilung der beiden Teile des Induktors in unabhängig voneinander elektrisch steuerbare Abschnitte gewählt werden.Alternatively or additionally, the inductor can also be divided into a plurality of electrically independently controllable sections. In this case, the inductor is thus not designed as a continuous electrical conductor, but constructed of electrically mutually insulated sections, which in turn, however, in their sum can have the approximated to an "8" outer contour. But it can also be provided to construct the inductor practically of two separate parts, which correspond in their outer shape to the two parts of the eyeglass bore, ie the respective overlapping housing bores. In this case, it is again provided that the regions close to the vicinity of the inductor have a greater distance from the inner surface than the regions which are further away from the gussets. Alternatively or additionally, a subdivision of the two parts of the inductor can also be selected in independently controllable sections.

Vorzugsweise wird in einem kurzen axialen Abstand hinter dem Induktor eine Kühlvorrichtung angeordnet, durch die die von dem Induktor beim Hindurchführen durch die Brillenbohrung erwärmten Oberflächenbereiche der Brillenbohrung beschleunigt abkühlbar sind. Diese Kühlvorrichtung ist vorzugsweise aus einem ähnlich einer "8" gebogenen, umlaufenden Verteilerrohr gebildet, dessen Kontur in ihrer Größe jeweils an die zu behandelnde Brillenbohrung angepasst ist. Dieses Verteilerrohr weist eine Vielzahl von radial nach außen und schräg gegen die vorgesehene Bewegungsrichtung der Vorrichtung angestellte Düsen für ein fließfähiges Kühlmittel, insbesondere für ein Kühlgas auf.Preferably, a cooling device is arranged at a short axial distance behind the inductor, by means of which the surface regions of the eyeglass bore heated by the inductor as it passes through the eyeglass bore can be cooled down more rapidly. This cooling device is preferably formed from a, similar to a "8" curved, circulating manifold whose contour is adapted in size to each of the eyeglass bore to be treated. This distributor tube has a multiplicity of nozzles for a flowable coolant, in particular for a cooling gas, positioned radially outwards and obliquely against the intended direction of movement of the device.

Nachfolgend wird die Erfindung anhand der in den Figuren schematisch dargestellten Ausführungsbeispiele näher erläutert. Es zeigen:

Fig. 1 - Fig. 4
Unterschiedliche Ausführungsformen erfindungsgemäßer Induktoren in einem Zylindergehäuse,
Fig. 5
eine Kühlvorrichtung in einem Zylindergehäuse und
Fig. 6
einen vergrößerten Ausschnitt aus der Gehäusewand eines Zylindergehäuses im Bereich des Zwickels.
The invention will be explained in more detail with reference to the embodiments schematically illustrated in the figures. Show it:
Fig. 1 - Fig. 4
Different embodiments of inventive inductors in a cylinder housing,
Fig. 5
a cooling device in a cylinder housing and
Fig. 6
an enlarged section of the housing wall of a cylinder housing in the region of the gusset.

Die Figuren 1-4 zeigen jeweils in einem Querschnitt ein Zylindergehäuse 1 mit einer aus zwei sich teilweise überlappenden Gehäusebohrungen gebildeten Brillenbohrung 2. Das Zylindergehäuse 1 ist aus einem Block eines härtbaren Stahls durch zerspanende Fertigungsverfahren hergestellt worden. Im Überlappungsbereich der beiden Gehäusebohrungen ist die Gehäusewand in Form der beiden Zwickel 4 a, 4 b gestaltet. Ein solcher Zwickel ist in der Figur 6 als Teilausschnitt vergrößert dargestellt. Die Innenoberfläche des Zylindergehäuses 1 soll so gehärtet werden, dass die gehärtete Schicht 17 nur eine sehr begrenzte Tiefe von z.B. 0,5 - 2 mm aufweist. Hierdurch soll vermieden werden, dass die Zwickel 4 a, 4 b durchgehärtet werden und so ihre Duktilität im Inneren verlieren.FIGS. 1-4 each show, in a cross-section, a cylinder housing 1 with a bore 2 made of two partially overlapping housing bores. The cylinder housing 1 has been produced from a block of hardenable steel by machining processes. In the overlap region of the two housing bores, the housing wall in the form of the two gussets 4 a, 4 b designed. Such a gusset is shown enlarged in the figure 6 as a partial detail. The inner surface of the cylinder housing 1 is to be hardened so that the hardened layer 17 has only a very limited depth of e.g. 0.5-2 mm. This is to avoid that the gussets 4 a, 4 b are cured and thus lose their ductility in the interior.

Im Inneren der Brillenbohrung 2 ist in Figur 1 ein elektrischer Induktor 3 angeordnet, der im Wesentlichen in Form einer liegenden "8" als zusammenhängender elektrischer Leiter beispielsweise aus einem Kupferrohr gebogen ist. Der Induktor 3 ist aus mehreren Teilstücken mit unterschiedlicher Krümmung zusammengesetzt. Die beiden Teilstücke 6 a und 6 b weisen jeweils einen konstanten Krümmungsradius auf, der gewährleistet, dass der Abstand dieser Teilstücke von der Innenoberfläche der Brillenbohrung 2 jeweils konstant ist. In unmittelbarem Anschluss an diese Teilstücke 6 a und 6 b sind die Teilstücke 7 a - 7 d vorgesehen, die in Richtung auf den Mittelbereich der "8" einen zunehmend kleineren Krümmungsradius aufweisen, so dass in diesen Bereichen sich der Abstand des Induktors von der Innenoberfläche der Brillenbohrung entsprechend vergrößert. Zur Verbindung der Teilstücke 7 a, 7 c bzw. 7 b, 7 d miteinander sind die beiden Gegenbögen 8 a und 8 b vorgesehen. Dabei ist der Gegenbogen 8 b im Prinzip geteilt ausgeführt, da an ihm die beiden elektrischen Anschlüsse für die Einleitung des Induktorstroms angeordnet sind. Diese Anschlüsse sind durch zwei kleine Kreise angedeutet.In the interior of the eyeglass bore 2, an electrical inductor 3 is arranged in FIG. 1, which is bent substantially in the form of a horizontal "8" as a continuous electrical conductor, for example, of a copper tube. The inductor 3 is composed of several sections with different curvature. The two sections 6 a and 6 b each have a constant radius of curvature, which ensures that the distance between these sections of the inner surface of the eyeglass bore 2 is constant. Immediately following these sections 6 a and 6 b, the sections 7 a - 7 d are provided, which have in the direction of the central region of the "8" an increasingly smaller radius of curvature, so that in these areas, the distance of the inductor from the inner surface the eyeglass bore increased accordingly. To connect the sections 7 a, 7 c and 7 b, 7 d together, the two opposing arches 8 a and 8 b are provided. In this case, the counter-bow 8 b is executed divided in principle, since the two electrical connections for the introduction of the inductor are arranged on it. These connections are indicated by two small circles.

In Figur 2 ist eine andere Ausführungsform des Induktors 3 dargestellt, bei der einzelne Teilstücke im Nahbereich der beiden Zwickel 4 a, 4 b elektrisch unabhängig voneinander steuerbar sind, also separate induktorstromanschlüsse aufweisen. Insgesamt bleibt bei diesem Induktor 3 der Abstand zur Innenoberfläche der Brillenbohrung 2 über den gesamten Umfang praktisch konstant. Der Induktor 3 besteht im vorliegenden Fall jeweils aus zwei kreisförmig gebogenen Teilstücken 9 a, 9 b, deren Umfang größer als bei einem Halbkreis ist. An jedem Ende der beiden Teilstücke 9 a, 9 b schließen sich nacheinander jeweils zwei kürzere Teilstücke 10 a, 11 a bzw. 10 b, 11 b bzw. 10 c, 11 c bzw. 10 d, 11 d des Induktors an. Die Teilstücke 10 a -10 d können, da sie symmetrisch in Bezug auf die innenkontur der Brillenbohrung 2 angeordnet sind, mit den gleichen elektrischen Parametern betrieben werden, also an die gleiche Stromquelle angeschlossen werden. Entsprechendesgilt für die Teilstücke 11 a - 11 d. Diese können im Vergleich zu den Teilstücken 9 a, 9 b zur Verminderung des spezifischen Wärmeenergieeintrags im Bereich der Zwickel 4 a, 4 b insbesondere mit vermindertem Induktorstrom und/oder zeitlich getaktet betrieben werden.In Figure 2, another embodiment of the inductor 3 is shown in which individual sections in the vicinity of the two gussets 4 a, 4 b are electrically controlled independently of each other, so have separate inductive power connections. Overall, in this inductor 3, the distance to the inner surface of the eyeglass bore 2 remains practically constant over the entire circumference. In the present case, the inductor 3 consists in each case of two circularly bent sections 9 a, 9 b whose circumference is greater than in the case of a semicircle. At each end of the two sections 9 a, 9 b close in succession in each case two shorter sections 10 a, 11 a and 10 b, 11 b and 10 c, 11 c and 10 d, 11 d of the inductor. The portions 10 a -10 d, since they are arranged symmetrically with respect to the inner contour of the eyeglass bore 2, are operated with the same electrical parameters, that are connected to the same power source. The same applies to the sections 11 a - 11 d. These can be compared to the sections 9 a, 9 b to reduce the specific heat input in the region of the gusset 4 a, 4 b in particular with reduced inductor and / or operated in time.

In Figur 3 ist eine Variante des Induktors 3 dargestellt, bei der insgesamt vier unabhängig voneinander elektrisch steuerbare Abschnitte 12 a, 12 b, 13 a, 13 b vorgesehen sind. Die beiden Abschnitte 12 a, 12 b weisen einen konstanten Krümmungsradius auf, während die in der Nähe der beiden Zwickel 4 a, 4 b angeordneten Induktorteilstücke 13 a, 13 b so gekrümmt sind, dass ihr Abstand von der Innenoberfläche mit zunehmender Annäherung an den Spitzenbereich des jeweiligen Zwickels 4 a bzw. 4 b größer wird. Zusätzlich ist vorgesehen, dass die beiden Teilstücke 13 a, 13 b mit gegenüber den beiden Teilstücken 12 a, 12 b verminderter elektrischer Leistung betrieben werden.FIG. 3 shows a variant of the inductor 3 in which a total of four independently controllable sections 12 a, 12 b, 13 a, 13 b are provided. The two sections 12 a, 12 b have a constant radius of curvature, while arranged in the vicinity of the two gussets 4 a, 4 b inductor sections 13 a, 13 b are curved so that their distance from the inner surface with increasing approach to the tip region of the respective gusset 4 a and 4 b is larger. In addition, it is provided that the two sections 13 a, 13 b are operated with respect to the two sections 12 a, 12 b reduced electrical power.

In Figur 4 ist eine Variante des Induktors 3 wiedergegeben, bei der dieser aus zwei Teilstücken 14 a, 14 b besteht, die jeweils mit gleichen elektrischen Parametern betrieben werden, also vorzugsweise an dieselbe elektrische Stromquelle angeschlossen werden. Ähnlich wie in Figur 1 und Figur 3 weist der Induktor 3 mit zunehmender Annäherung an die beiden Zwickelbereiche 4 a, 4 b einen größer werdenden Abstand von der Innenoberfläche der Brillenbohrung 2 auf.In Figure 4, a variant of the inductor 3 is shown, in which this consists of two sections 14 a, 14 b, which are each operated with the same electrical parameters, that is preferably connected to the same electrical power source. Similar to Figure 1 and Figure 3, the inductor 3 with increasing approach to the two gusset regions 4 a, 4 b an increasing distance from the inner surface of the eyeglass bore 2.

In Figur 5 ist eine Kühlvorrichtung 15 innerhalb einer Brillenbohrung 2 eines Zylindergehäuses 1 dargestellt, die in axialem Abstand hinter dem hier nicht dargestellten Induktor angeordnet ist und zusammen mit dem Induktor durch die Brillenbohrung 2 in audater Richtung hindurchgeführt wird. Diese Kühlvorrichtung 15 ist in Form eines umlaufenden Verteiterrohres ausgebildet, das im Wesentlichen in Form einer "8" gebogen ist und insoweit an die Kontur der Brillenbohrung 2 angepasst ist. Das Verteilerrohr ist mit einer nicht dargestellten Zufuhrleitung für ein Kühlmedium sowie an seinem Umfang mit zahlreichen radial nach außen gerichteten Düsen 16 versehen, durch die ein gasförmiges oder flüssiges Kühlmedium austreten kann. Die Düsen 16 sind bezogen auf die Bewegungsrichtung des Induktors während des Härtevorgangs schräg nach hinten gegen die Bewegungsrichtung angestellt, damit nicht die noch aufzuheizenden Bereiche der Innenoberfläche gekühlt werden, sondern lediglich die bereits auf Härtetemperatur gebrachten Oberflächenbereiche.In Figure 5, a cooling device 15 is shown within a spectacle bore 2 of a cylinder housing 1, which is arranged at an axial distance behind the inductor, not shown here and is passed together with the inductor through the eyeglass bore 2 in the audatory direction. This cooling device 15 is designed in the form of a circulating Verteiterrohres, which is bent substantially in the form of an "8" and in this respect is adapted to the contour of the eyeglass bore 2. The manifold is provided with a supply line for a cooling medium, not shown, as well as at its periphery with numerous radially outwardly directed nozzles 16 through which a gaseous or liquid cooling medium can escape. The nozzles 16 are made obliquely backwards with respect to the direction of movement of the inductor during the hardening process against the direction of movement, so that not the still heated areas of the inner surface are cooled, but only the already brought to hardening temperature surface areas.

Mit der vorliegenden Erfindung lassen sich Zylindergehäuse von Doppelschneckenextrudern sehr viel kostengünstiger mit einer weitgehend gleichbleibend dicken Härteschicht im Bereich der Innenoberfläche versehen, als dies bisher der Fall war, da eine aufwendige Glühbehandlung des gesamten Zylindergehäuses in einem Ofen unterbleiben kann. Dabei wird nicht nur eine erhebliche Energieeinsparung erzielt, sondern es wird auch eine drastische Verkürzung der Behandlungsdauer erreicht. Wesentlich ist, dass mit der erfindungsgemäßen Verfahrensweise und durch den Einsatz eines erfindungsgemäßen Induktors eine unerwünschte Durchhärtung der Zwickeibereiche unterbleibt.With the present invention, cylinder housings of twin-screw extruders can be provided much more cost-effectively with a largely uniformly thick hardening layer in the region of the inner surface than has hitherto been the case, since elaborate annealing of the entire cylinder housing in a furnace can be omitted. Not only a considerable energy saving is achieved, but it is also achieved a drastic reduction in treatment time. It is essential that with the procedure according to invention and by the employment of an inductor according to invention an unwanted hardening of the Zwickeibereiche stops.

Claims (13)

  1. Method for manufacturing a cylindrical casing for a double screw extruder whose screws mesh with each other, with an abrasion-resistant inner surface, made from a block of steel by putting two holes that pass right through and that partly overlap each other (spectacle hole) into the steel block, and subsequently hardening the inner surface of the spectacle hole,
    characterised in that
    the hardening process is in the form of inductive hardening with an essentially consistent penetration depth, in that an electrical inductor with a shape that is approximately the same as the inner contour of the spectacle hole but reduced in size is passed from one end of the spectacle hole to the other, an inductor being used that is designed so that, in the immediate vicinity of the two narrow parts of the spectacle hole in relation to the corresponding lengthwise section on the perimeter of the inductor, in each case far less energy is released for heating the inner surface of the spectacle hole than in the areas of the inner contour that are further away from the narrow parts.
  2. Method as in claim 1,
    characterised in that
    at an axial distance behind the inductor, a cooling appliance is passed through the spectacle hole for the accelerated cooling of the inductively heated areas.
  3. Method as in claim 2,
    characterised in that
    a liquid or gaseous coolant is used for the accelerated cooling process.
  4. Method as in one of claims 1 to 3,
    characterised in that
    the inductor is passed through the spectacle hole at a far greater distance from the inner surface in the immediate vicinity of the two narrow parts than in the remaining area of the inner surface.
  5. Method as in one of claims 1 to 4,
    characterised in that
    an inductor is used that has, along the length of its perimeter, sections that can be electrically controlled independently of each other.
  6. Method as in one of claims 1 to 5,
    characterised in that
    prior to the final operation of the mechanical treatment of the steel block, the inner surface of the spectacle hole is provided with a hardenable plating material.
  7. Device for the inductive hardening of the inner surface of a spectacle hole (2) in a cylindrical casing (1) made of steel for a double screw extruder, for the purpose of carrying out the method as in claim 1, with an electrical inductor (3), the external shape of which is approximately the same as a reduced form of the inner contour of the spectacle hole (2), the inductor (3) being shaped in such a way that, in the immediate vicinity of the two narrow parts (4 a, b) of the spectacle hole (2) in relation to the corresponding lengthwise section on the perimeter of the inductor (3), in each case far less energy is released for heating the inner surface than in the areas of the inner surface that are further away from the narrow parts (4 a, b).
  8. Device as in claim 7,
    characterised in that
    the inductor (3) is curved from an electrically conductive tube through which can be passed a coolant, to form a continuous electrical conductor (5) with the approximate external contour of a figure 8, the top and bottom areas (6 a, b) of the figure 8 each being curved in a circular shape, while with increasing proximity to the central area of the figure 8, there adjoins in each case an area (7 a - d) with an increasingly smaller radius of curvature, and in the central area of the figure 8 there is in each case a counter-curve (8 a, b) for the purpose of joining up with the areas (7 a - d) that have a smaller radius of curvature.
  9. Device as in claim 7 or 8,
    characterised in that
    the inductor is divided into a number of sections (9 a - 11 d; 12 a - 13 b; 14 a, b) which can be electrically controlled independently of each other.
  10. Device as in one of claims 7 to 9,
    characterised in that
    at an axial distance behind the inductor (3) there is a cooling device (15), by means of which the surface areas of a specacle hole (2) heated by the inductor (3) during its passage through the spectacle hole (2) can be rapidly cooled.
  11. Device as in claim 10,
    characterised in that
    the cooling device (15) is made up of a distributing tube curved like a figure 8 and running right round, the outer contour of which is adapted in each case to the spectacle hole (2) that is to be treated, and which has a large number of nozzles (16) for a free-flowing coolant, in particular a coolant gas, which nozzles are set radially outwards and at an angle to the intended direction of movement of the device.
  12. Device as in claim 8,
    characterised in that
    the electrically conductive tube is a copper tube.
  13. Device as in claim 11,
    characterised in that
    the coolant is a coolant gas.
EP02729775A 2001-03-08 2002-03-07 Production of a cylindrical housing for a double screw extruder Expired - Lifetime EP1366199B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10112295A DE10112295B4 (en) 2001-03-08 2001-03-08 Manufacture of a barrel of a twin screw extruder
DE10112295 2001-03-08
PCT/DE2002/000876 WO2002070754A2 (en) 2001-03-08 2002-03-07 Production of a cylindrical housing for a double screw extruder

Publications (2)

Publication Number Publication Date
EP1366199A2 EP1366199A2 (en) 2003-12-03
EP1366199B1 true EP1366199B1 (en) 2006-03-01

Family

ID=7677455

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02729775A Expired - Lifetime EP1366199B1 (en) 2001-03-08 2002-03-07 Production of a cylindrical housing for a double screw extruder

Country Status (5)

Country Link
US (1) US6881934B2 (en)
EP (1) EP1366199B1 (en)
JP (1) JP4255694B2 (en)
DE (2) DE10112295B4 (en)
WO (1) WO2002070754A2 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090057300A1 (en) * 2007-08-27 2009-03-05 Xaloy Incorporated Heating system for plastic processing equipment having a profile gap
WO2012002862A1 (en) * 2010-07-02 2012-01-05 Aktiebolaget Skf Mechanical component and method of surface hardening
DE102013110671B4 (en) * 2013-09-26 2018-05-24 Kraussmaffei Berstorff Gmbh Wear body for receiving a twin screw for the extrusion of meltable material
RU2570262C1 (en) * 2014-06-03 2015-12-10 Открытое акционерное общество "Завод им. В.А. Дегтярева" Thermal processing of automatic gun barrel pin
CN105171345B (en) * 2015-08-28 2017-04-12 南通高欣耐磨科技股份有限公司 Preparation method for high-wear-resistance and repairable conical double cylinders
DE102015221758A1 (en) * 2015-11-05 2017-05-11 Coperion Gmbh Screw machine and process for the treatment of material to be processed

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Publication number Priority date Publication date Assignee Title
DE896240C (en) * 1943-04-28 1953-11-09 Deutsche Edelstahlwerke Ag Inductor for progressive electro-inductive hardening
DE1816734U (en) * 1958-04-03 1960-08-18 Siemens Ag DEVICE FOR INTERNAL COOLING OF PREFERABLY INDUCTIVELY HEATED PIPES OR WORKPIECE HOLES.
US4401485A (en) * 1981-07-22 1983-08-30 Park-Ohio Industries, Inc. Method for inductively heating thin-walled elongated workpieces
US4375997A (en) * 1982-05-13 1983-03-08 General Motors Corporation Method of inductively heat treating a thin-walled workpiece to control distortion
JPS5837369B2 (en) * 1982-06-15 1983-08-16 株式会社 第一高周波本社 How to heat the inner surface of a metal tube
DE3521174A1 (en) * 1984-07-02 1986-01-23 Uni-Cardan Ag, 5200 Siegburg CV JOINT, IN PARTICULAR FOR DRIVE SHAFTS WITH HIGH SPEED
DD283159A5 (en) * 1989-05-16 1990-10-03 Karl Marx Stadt Maschf FLAME HOLDING DEVICE, IN PARTICULAR OF CYLINDER HOLES IN MULTI-CIRCULAR EXTRUSORS
US5304000A (en) * 1993-07-28 1994-04-19 Apv Chemical Machinery Inc. Methods of constructing paddle and shaft assemblies for twin screw mixer and/or processors and the resulting apparatus
DE19915264C1 (en) * 1999-04-03 2000-06-21 Daimler Chrysler Ag Hollow workpiece, especially a vehicle transmission component e.g. a joint housing, is induction surface hardened by lowering an inductor and an overhead quench nozzle relative to the workpiece wall

Also Published As

Publication number Publication date
US6881934B2 (en) 2005-04-19
WO2002070754A3 (en) 2002-10-31
DE50205943D1 (en) 2006-04-27
US20040074092A1 (en) 2004-04-22
WO2002070754A2 (en) 2002-09-12
EP1366199A2 (en) 2003-12-03
DE10112295B4 (en) 2004-07-29
DE10112295A1 (en) 2002-09-26
JP4255694B2 (en) 2009-04-15
JP2004536721A (en) 2004-12-09

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